Actually

I prefer to do most of my laser-cutting purely in 2D. The open-source vector software Inkscape totally rocks my socks off, and I can design things about three times faster using that than anything else.

When a design gets a little complicated, though, or it’s hard to see how everything fits together, it’s sometimes easier to model everything in 3D right from the start. So I built a linear actuator with SolidWorks.

If you can’t see, it’s a DC motor that rotates a threaded rod, with that slider piece in the middle holding a captive nut and a rod. You drive the motor, the rod goes in (or out).

This was just a proof-of-concept to see how it all fit together. I wasn’t really happy with:

The amount of material it used up

The physical size

Way too much friction in the system

Possible strength issues in the rod

No way to read or track the rod position.

Solution: Mark II.

Replace the DC motor with a stepper

Triangular chassis for less material usage and size

#10 threaded rod instead of 1/4″, also for size

Add some bearings

Triple up the actuator rod.

It’s very slow, but that’s simply a matter of choosing different motors and is acceptable for now.

The bearings I had on hand are standard axial bearings; totally not suited to radial loads. That’s something I’ll have to come back to. I saw a method of laser-cutting the races to make custom thrust bearings recently, I’ll have to see if that’s appropriate for this application.